Effects of soil osmotic potential produced with two salt species on plant water potential, growth, and grain yield of wheat

Abstract

Wheat plants (variety Inia 66) were grown under various soil osmotic potential levels produced with NaCl and CaCl2. Experiments were conducted under controlled environmental conditions in a growth chamber. High salinity in the rooting medium reduced transpiration and grain yield and increased leaf resistance to water diffusion. Leaf total water potential and osmotic potential were decreased with increasing soil salinity. The effect of CaCl2 was always greater than the effect of NaCl on all growth responses. However, Inia 66 showed high tolerance to salinity. The soil osmotic potential associated with a 50% grain yield decrement was −7.3 bars with NaCl, twice the previously reported limit for wheat. The same osmotic potential produced with CaCl2 caused a 75% decrease in grain yield. Leaf turgor pressure was constant and unaffected by decreasing the osmotic potential of the soil solution due to a parallel decrease in the total and osmotic potentials of the plant leaves. The results suggest that neither osmotic adjustment nor water availability theories explain the greater effect of CaCl2 on wheat growth reduction. A different mechanism is proposed in which plant cell walls lose their elasticity and cell elongation is inhibited.